Distinctly Human

The when, where & how of life's beginnings

Ever since President George W. Bush announced his decision regarding federal funding of research on human embryonic stem cells last year, newspapers worldwide have reported on various issues surrounding such research. Many people are confused about the status of the embryo. Is it a human being? Is it a person? Is it "one of us"? These are questions not only of biology but also of philosophy.

From experience, all know that a newborn baby is quite different from a child. It is different in size, form, physical ability, mental acuity, and in countless other ways. Everyone realizes also that a child is different from an adolescent, an adolescent from an adult, and an adult from an octogenarian. These differences reflect developmental changes in a person. They are part of the cycle of life.

Neuroanatomists have established that the brain is not completely formed in the womb. The brain of the newborn baby continues to develop anatomically for the next two years. New brain cells appear, differentiate, and migrate to different areas of the brain during this period. Neuro-anatomists have established also that when an individual reaches eighteen, about fifty thousand cerebral-cortical cells wither and die each day during the rest of life. Recently we learned that the human brain has the capacity to develop new cells to replace dead ones. Thus the process of growth, decline, and replacement in the brain is a part...

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About the Author

John Collins Harvey, M.D., is professor of medicine, emeritus, at Georgetown University Medical Center, Washington, D.C.